Toy wagons have existed for years. Children take great delight in playing with wagons. Many adults have fond memories of pulling their wagon (usually red) around or riding in it having someone else do the pulling.
A traditional wagon has four wheels and a pulling handle in front. The wagon is steered by moving the tongue handle from side to side; this turns the front wheels. Many children would like to push their wagon from behind. However, traditional wagons are difficult to push from behind because the steering tongue handle does not reach back to the rear. In addition, some children would like to use their wagon much like a scooter, where the wagon is pushed from behind to gain momentum and the pusher then jumps on board to ride. The rear wall of a traditional wagon impedes the pushing child from stepping on board to ride the wagon like a scooter.
Furthermore, a more traditional wagon can be very bumpy to ride. Many neighborhoods suffer from sidewalks and streets with cracks and holes. When a wagon wheel hits a crack or hole, the whole wagon is jarred.